In the field of graphic arts, an image-formation system having super-hard photographic character is required to improve reproduction of images with continuous gradation of half-tone images or to improve reproduction of line images.
Previously, a particular developer known as a lith-developer has been utilized for the above purpose. A lith-developer contains only hydroquinone as a developing agent, in which a sulfite preservative is incorporated in the form of an adduct with formaldehyde in order not to interfere with the infectious developability thereof. Thus, the concentration of free sulfite ion in the developer is extremely low (generally, 0.1 mol/liter or less). Accordingly, the lith-developer is easily subjected to aerial oxidation and therefore has a serious defect in that it is not stable during storage for more than 3 days.
Known methods for obtaining high-contrast photographic characteristic by using a stable developer include using a hydrazine derivative, for example, as described in U.S. Pat. Nos. 4,224,401, 4,272,606, 4,211,857 and 4,243,739, and high-contrast systems using a tetrazolium derivative, for example, as described in JP-A-53-17719 and 61-117535. (The term "JP-A" as used herein means an "unexamined published Japanese patent application".)
Recently, scanner systems have become widely used in the field of photomechanical processing and printing technology. There are various known recording apparatus for image formation using such a scanner system. As a recording light source for this type of scanner system recording apparatus, a glow lamp, xenon lamp, tungsten lamp, LED, He-Ne laser, argon laser, semiconductor laser, etc are known.
Photographic materials which are applied to scanner systems of this type, must possess various photographic characteristics. In particular, the photographic materials are required to have high sensitivity and high contrast even under short time exposure, since they are only exposed from 10.sup.-7 to 10.sup.-3 seconds. Especially in the field facsimile machines, the photographic materials used therein must have rapid processability which is considered the most important characteristic in the field.
In the future, increasing the number of lines to be resolved as well as focusing the light beam to be irradiated would be required for the purpose of further accelerating scanning speed and further improving the quality of images to be reproduced. In this situation, development of photographic materials which have high sensitivity and high contrast and which may be developed and processed rapidly is strongly desired.
Further, various apparatus having an automatic feeding mechanism such as an automatic device for automatically feeding, exposing and developing photographic materials have been developed recently, and such automatic apparatus have been applied to a recording device used with the above-mentioned scanner system.
Where photographic materials are fed by the use of such an automatic feeding system, various feeding accidents often occur during the automatic processing. For example, photographic materials being processed can be erroneously trapped and stopped in the course of the processing line, or where large-sized sheet films are fed one by one from a sheet tray or stack zone, two or more sheets of them are erroneously fed (double-feeding).
As a means of improving the feedability of photographic materials being processed, there has been known a method of reducing the sliding friction of the materials. For instance, various techniques for this method are described in U.S. Pat. Nos. 3,042,522 and 3,080,317, and British Patents 1,466,304 and 1,143,118.
However, where photographic materials are processed with the more recent automatic processing machines equipped with a variety of feeding mechanisms as mentioned above, simply improving the slide property to the photographic materials being processed can not ensure sufficient feedability of the materials into the machine.
On the other hand, JP-A-60-188942, 60-188945 and 1-37710 disclose a system for improving the feedability of photographic materials by adding a mat agent to the backing layer of the support of the material, in which the mat agent containing grains having a grain size of 5 .mu.m or more in a proportion of 30% or more by volume. However, the disclosed system is still not satisfactory, though it would be effective for improving the feedability of photographic materials being processed.
Additionally, it has been found that the disclosed system has a drawback. Specifically, since the mat agent contains large grains having a grain size of 5 .mu.m or more in a proportion of 30% or more by volume, and therefore the volume of each grain in the agent is large, the number of grains present in the backing layer of the photographic material must be small even though the mat agent is incorporated into the backing layer of the material. As a result, when the material containing the agent is wound up on a roll, or a number of sheets of the material are piled up, the load to be applied to the unit area of the mat agent grain is so large that the mat agent grains in the layer can easily be crushed and broken out. Further, the system has been found to have another drawback. Specifically, when a mat agent comprising large grains is to be incorporated into a photographic material, the precipitation speed of the mat agent grains in the coating composition is large so that the content of the mat agent in the photographic material noticeably fluctuate in every manufacture lot of photographic materials.